This is a renewal application for the operation of the core facilities of the Reproductive Endocrinology Center of the University of California, San Francisco. The core facilities include: (1) Radioimmunoassay Laboratory, (2) Tissue Culture Core, (3) Morphology Core, (4) Primate Facility, (5) Analytical Separation Core, and Administrative Core. The Reproductive Endocrinology Center is an integrated, interdepartmental research and training program at the University of California, San Francisco. It was established to study hormonal regulation or reproductive events at the subcellular, cellular, and tissue and whole organism levels. A variety of species, including subhuman primates and humans, is being studied with the overall goal being to understand the physiologic and pathophysiologic regulation of the reproductive process in humans. More specifically, this is a multifaceted program with the primary foci being studies of the hypothalamic-pituitary-gonadal-target tissue axis and the endocrine physiology of pregnancy. Currently, there are 14 faculty members on the staff of the Reproductive Endocrinology Center from the following departments: Obstetrics, Gynecology and Reproductive Sciences, Anatomy, Physiology, Biochemistry and Biophysics, Pathology, Internal Medicine, Laboratory Medicine and the Hormone Research Laboratory. The existence of the core facilities has permitted the maximal development and use of frequently employed research procedures, has increased collaboration and interchange between the members of the Reproductive Endocrinology Center, has avoided unnecessary duplication and thus has been, and continues to be, cost-effective.